Stable and Efficient Upconversion Single Red Emission from CsPbI₃ Perovskite Quantum Dots Triggered by Upconversion...

Here, composites including highly efficient inert shell-modified NaYF₄:Yb/Tm@NaYF₄ upconversion nanoparticles (UCNPs) and CsPbI₃ perovskite quantum dots (PQDs) have been successfully synthesized by the assistance of (3-aminopropyl)triethoxysilane (APTES) as a precursor for a SiO₂ matrix. UCNPs and CsPbI₃ PQDs in this composite structure show excellent stability in ambient conditions. Importantly, the efficient UC emission of CsPbI₃ PQDs was realized, which means that the single red emission of inert shell-modified UCNPs can be easily obtained by depending on these composite structures. Furthermore, the single red emission wavelength can be easily regulated from 705 to 625 nm by introducing appropriate proportion of Br^- ions, which is very difficult to achieve for traditional UCNPs. Moreover, benefiting from the efficient downshifting (DS) red emission of CsPbI₃ PQDs, the composites possess the dual-wavelength excitation characteristics. So, the excellent dual-mode anticounterfeiting application has been demonstrated. This work will provide a new idea for the development of perovskite-based multifunctional materials.